1. Field of the Invention
The present invention relates generally to devices for dispensing viscous fluids including such diverse materials as grease and joint compound. More specifically, the present invention is concerned with dispensing devices which are hand-held and have provisions for discharging a viscous fluid from and charging a viscous fluid to a canister through a common conduit.
2. Description of the Prior Art
U.S. Pat. No. 2,430,608 discloses a service station installation including stationary grease pumps operated by compressed air, electricity or the like and mounted on grease drums. Such apparatus is in wide use and works very well in locations having a readily accessible source of compressed air or electricity.
Hand-held, manually operated grease guns are also known. Such grease guns are designed for use with a grease canister and include a manually operated mechanism for pressurizing grease and causing it to flow out of the through a conduit to a suitable coupling.
U.S. Pat. No. 3,987,869 entitled "Back Pack Lubrication System" discloses a motorized, back pack mounted grease dispensing device. The device includes grease cylinders and spring urged pistons for pressurizing grease within the cylinders, a conduit connecting the grease cylinders to a pump and a conduit connecting a discharge port of the pump to a grease gun. This device also includes a motor to supply shaft power to the pump and a battery power pack for supplying current to the motor. The patent discloses that the pump can be of the auger-type or of the piston type. The grease cylinders are provided with a detachable cap to enable the operator to remove the piston and refill the grease cylinders.